upon the Leaf of a Plant belonging to the Order Ochnaceae. 577 



The discovery of the exuviae in some of them, in addition to a microscopic- 

 examination, placed it beyond all doubt that I had before me the production 

 of an insect. 



Twenty or more individuals are produced on the same leaf (in that before 

 nie twenty-three), the upper surface of which is furnished with a strong shining 

 cuticle. As soon as the presence of the grub has caused the tissue imme- 

 diately around it to swell, and to detach itself above and below, by a sort of 

 concentration, from the cuticle, there is an evident attempt, as it enlarges, 

 exactly as in ^cidium cancellatum and other allied epiphytal Fungi, to burst 

 indifferently through either surface, but, apparently, it is in general unable 

 to overcome the superior resistance of tlie upper cuticle, though that is 

 somewhat raised and occasionally a little ruptured, and consequently forces 

 its way through the hypophyllous cuticle, splitting it into a few subacute 

 lacinise. 



Each gall is cylindrical, about a line long, and consists of two distinct sub- 

 stances, the outer of which is dark brown, and evidently a continuation of the 

 inner substance of tiie leaf; tlie inner much paler, thinner, shining and horny, 

 as is indeed the case in many galls. The apex is strongly umbilicate with the 

 border, which is formed of the outer coat, slightly expanded, and furnished 

 with a few shallow, obtuse, distinct crenulations. At the bottom of the um- 

 bilicus is a nipplelike operculum. The operculum is solid and formed of the 

 outer coat, but is intimately connected with tlie top of the inner horny sac, 

 which is very thin above, and thus forms a lid to it, which fits on exactly 

 where the outer suddenly diverges from the inner coat, so that little resistance 

 is offered to the egress of the insect, except that of the upper portion of the 

 inner coat, which, as said above, is extremely thin, and, at the point where the 

 operculum fits on, very brittle. There is sometimes a little punctiform de- 

 pression at the top of the opercidum, which is probably the scar of the punc- 

 ture made by the ovipositor of the insect. Seventeen of the galls were already 

 burst; and out of the remaining six, one only furnished an imperfect grub, 

 and this being exceedingly light and dry, was unfortunately lost whilst the 

 drawing was in progress. Several of the other galls had the remains of exuviae, 

 but too imperfect to furnish any information. I am not aware that there is 

 any instance on record of a gall bursting through the cuticle; and the oper- 



